Impact device control system



y 1964 H. ZOLLINGER, JR 3,133,472

IMPACT DEVICE CONTROL SYSTEM Filed Sept. 5, 1961 HE -11g! SOURCE I E2 '1 42,2 w Hk INVENTOR.

-l4 /50 [M H34 BY Q 22 W Mfg W A 7' TORNEYS 7 HENRY ZOLLINGER JR #2 United States Patent 3,133,472 IMPACT DEVICE CONTROL SYSTEM Henry Zollinger, Jr., Cheshire, Conn., assignor to Electro- Mechanics Inc., New Britain, Conn., a corporation of Connecticut Filed Sept. 5, 1961, Ser. No. 136.023 24 Claims. (Cl. 91-165) This invention relates generally to impact devices and more particularly to a pneumatic control system for an impact device having an impact member that is driven between an impacting position and aretracted position by control the rate of impacts of the impact member over a a a large frequency range without diminishing the stroke of the impact member or its impacting force.

It is a further object of this invention to provide an improved control system for an impact device which is adjustable for varying the impacting force of the impact member and with which the impacting force remains constant without periodic readjustment of the controls.

It is another object of this invention to provide an improved control system for an impact vibrator which has a minimum number of parts that can be readily assembled and which reliably controls the operation of the impact member between its retracted and impact positions.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth and the scope of the application which will be indicated in the appended claims.

The drawing is a diagrammatic view of an impact device and an embodiment of a control system of this invention.

Referring to the drawing in detail, the control system of this invention is shown with an impact device, generally designated by the numeral 8, which comprises an inner cylinder 10 and an outer housing 12 which slideably supports an impact anvil 14. An impactpiston 16 is reciprocably mounted in the cylinder 10 for movement between a retracted position, shown in the drawing, and

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wardly against the anvil 14 and is thereafter re-supplied to retract or force the piston upwardly.

The cushion of air formed above the aperture 18 acts to rapidly decelerate the piston as it approaches the top of its stroke, and consequently, it ensures that the piston does not strike the housing 12 at the top of its stroke and that the entire impact stroke is used. A conduit 22 leading to the cylinder 10 is closed off by the piston 16 when it is in its up or retracted position, but is opened when the piston is in the impact position to receive fluid from above the piston having the first regulated pressure thereby providing a means for sensing when the piston is in the impact or down position. I

lnaccordance with this invention, a control system is provided for controlling and regulating the fluid supplied by the conduits 24 and 26 so as to control the movement of the piston 16 between its impact and retracted positions.

Included within this control system are a first pressure regulator valve R a second pressure regulator valve R a throttle valve T, a cycle control valve V and a cyclesensing valve V A supply of pressurized fluid, preferably air, is connected to the regulator valves R1 and R via an inlet conduit 30. The regulator valve R is shown with an air valve 42 that isadapted to be opened by an extension 40 fixed to-a slidably mountedipiston 36. The regulated air pressure of a fluid r in the regulator outlet conduit 24 has a value depending upon the bias of the spring 34 on the piston 36 and is manually adjustable by the handle 32. I

The regulator valve R is'designed to provide a fluid r in the outlet conduit with a second regulated pressure that has a magnitude which is greater than the pressure of the fluidr by a substantially fixed amount which is preferably 15 .to 20 p.s.i. as determined by the preset downward or opening bias placed upon the valve 41 resulting from the springs 44 and 47. The fluid f is supplied to the chamber 43 abovega piston 46 to increase the opening bias on the piston 46, and the fluid r is acting against the opening bi as on the underside of the piston 46; therefore, the valvepiston 48 opensor closes the conduit 30 when the, force created by the fluid r is respectively less or greater than the force created by the fluid r plus the opening bias resulting from the springs 44 and 47.

Referring to the cycle-sensing valve V a spool valve member60 has three-valve lands 62, 64 and 66 that coan impact position where the piston engages the anvil 14 for directing the kinetic energy of the piston to an' associated device (not shown). An aperture or passage; 18 connects the cylinder 10 and a fluid reservoir orplenum chamber 2t) formed between the housing 12 and cylinder ill and is spaced from the upper end of the cylinder 10 to provide a piston cushion chamber generally designated 19. The impact piston is moved to its retracted and impact positions by a compressible pressurized fluid (normally air) that is supplied by the conduits 26 and 24 to the lower and upper ends of the pistons 16, respectively. Generally, the conduit 24 supplies a fluid having a first regulated pressure to the cylinder 10 above the piston 16 via the reservoir chamber 20 and the passage 18, and the conduit 26 supplies a fluid having a second regulated pressure which is higherthan the first regulated pressure to the lower end of the cylinder 10 below the piston 16. The fluid in the conduit 26 is periodically exhausted to allow the fluid above the piston to move the piston downoperate with passages 68, and 72-,'respectively, in the valve body for selectively preventing flow of fluid therethrough. The valve member .60 has essentially two positions; a first non-sensingor down position, as viewed in the drawing, whereat the land 62- blocksthe passage 68 and the passages 70, -72 are open; and a second sensing orup position whereat-the passage68 is opened and the passages 70, 72 are blocked by the lands 64 and 66, re spectively; A spring 74 biases the valve member 60 downwardly to the first position whereupon the throttle inlet and outlet conduits 75 and 88, respectively, are connected to a valve chamber 82 which is in turn connected to exhaust. As soon as the piston 16 engages the anvil 14, a sensing fluid is directed to a chamber via the sensing conduit 22 for overcoming the bias of the spring 74 and forces the valve member 60 upwardly to the second or sensing position, whereupon the fluid r in the conduit 50 is directed to the throttle inlet conduit 75 and the throttle outlet conduit 88 is blocked.

Referring to the throttle valve T, a handle is provided for manually adjusting a needle valve 93 disposed between the throttle inlet conduit 75 and the outlet conduit 88 for controlling the rate of flow of fluid passing therebetweenand, therefore, the rate of increase in pressure of the fluid t in the throttle outlet conduit.

Referring to the cycle control valve V a valve member 100 has secured thereto a pair of diaphragms 102 and 104 that define fluid chambers 106, 108 and 110 which are connected for receiving fluid r the throttle outlet fluid t, and the fluid r respectively. The valve member 100 is biased downwardly, as viewed in the drawing, by a spring 112, the bias of which is shown to be manually adjustable by a handle 114. The valve member 100 has at its lower end an annular flange 116 that is adapted to abut an annular housing flange 118 when the valve 100 is in the piston extending or up position as viewed in the drawings, whereupon the conduit 26 is fluidly connected to exhaust via the valve chambers 130 and 140'and the exhaust passage 150. The valve member 100 has a pair of seals or rings 120, 122 so that when the valve member 100 is in the up position, the seal 122 engages the inner circumferential surface of the flange 118, whereas the seal 120 is out of engagement with the valve housing to connect the chambers 130 and 140. When the valve member 100 is in the lower or piston retracting position, the seal 120 engages the inner circumferential surface 136 of the valve housing to disconnect the chambers 130 and 140; whereas the seal 122 becomes disengaged with the inner circumferential surface of the radial flange 118 to connect the chambers 110 and 130 and thereby allow fluid r in the chamber 110 to be directed via the conduit 26 to the underside of the piston 16. Extending within the chamber 140 is a valve stem 142 that is actuated by the lower surface of the valve 100 when it moves to its down position thereby opening a valve 144 against the closing bias of a spring 146, and connecting the sensing conduit 22 with the exhaust conduit 150 for exhausting the pressure in the chamber 80.

The valve member 100 is readied to move to the up or piston-extending position when the throttle outlet fluid t in the chamber 108 is exhausted, as the upward force on the valve member 100 created by the fluid r in the chamber 110 is designed to be greater than the downward force on the valve member 100 created by the fluid r in the chamber 106 and the downward bias of the spring 112. To accomplish this relationship between the forces created by fluids r and r the effective area upon which the fluid r acts when the valve member 100 is downi.e., the area of the diaphragm 102 minus the area of the flange 116-must be related to the eflective area upon which the fluid r acts-i.e., the area of the diaphragm 104so that the fixed difference in the pressure of the fluids 1' and r is sufficient to overcome the bias of spring 112. The upward actuation of the valve member 100 is then accomplished by a snap action, since, when the seal 122 engages the inner circumferential surface of the flange 18, the downward force created by the fluid r on the flange 116 is terminated.

When the pressure of the throttle fluid t increases in the chamber 108, there is created a downward force uponthe valve member 100 which overcomes the upward force thereon and thereby moves the valve member 100 downwardly to the piston-retracting position. This downward actuation of the valve member 100 is accomplished with a snap movement or self-energization, because when the seal 122 becomes disengaged with the inner circumferential surface of the flange 118, there is a reduction in the pressure of fluid r in the chamber 110 due to the rapid expansion of the fluid into the chamber 130, conduit 26, and cylinder and there is an increased downward force upon the valve member 100 due to the force on the flange 116 created by the fluid r in the chamber 130.

Operation To simplify the understanding of the control system and the interrelated movements of the valves therein, the operation of the control system will be explained beginning with the cycle valve V the sensing valve V and the vibrator piston 16 in the positions shown in the drawing. At this point in the cycle with the cycle valve V in the piston-extending position, the pressure below the piston 16 and in the conduit 26 is connected to the exhaust conduit 150. Therefore, the fluid r in the chamber 20 and the fluid cushion above the piston 16 will force the piston 16 downwardly to impact or strike the anvil 14 with the magnitude of impact created by the piston being a function of the initial velocity imparted to the piston by the fluid cushion and the pressure of the fluid r As soon as the piston 16 engages the anvil 14, the fluid r above the piston 16 is directed through the sensing conduit 22 to the chamber to actuate the valve member 60 upwardly against the bias of the spring 74 for admitting fluid r from the conduit 50 to the throttle inlet conduit 75 via the passage 68 and for blocking the exhaust passages 70 and 72. The pressure of the throttle fluid t in the conduit 88 will begin to increase nearly simultaneously with the engagement of the piston 16 with the anvil 14 and will increase at a rate determined by the setting of the throttle needle valve 93. The pressure of the fluid t in the chamber 108 increases until it is suflicient to overcome the upward bias on the valve member for moving the valve downwardly to the piston retracting position. With the valve member 100 in the retracting position, fluid r in the chamber 110 is admitted to the lower end of the cylinder 10 at a rapid rate via the chamber and the conduit 26 to return the piston 16 to its up or retracted position. After the valve member 100 reaches its lower or piston retracting position, and concurrently with the upward movement of the piston 16, the sensing fluid in the chamber 80 is exhausted via the sensing conduit 22, the valve 144, chamber and the exhaust passage and the valve member 60 is returned to its lower or non-sensing position by the spring 74. As soon as the valve member 60 is returned to its lower position, the throttle valve inlet and outlet conduits 75 and 88 are connected to exhaust and the pressure of the fluid t in the cycle valve chamber 108 is reduced to atmospheric pressure. Accordingly, the valve member 100 returns to its up position as soon as the pressure in the chamber 110 builds up to a value that will overcome the downward bias created by the spring 112 and the fluid r acting on the diaphragm 104. As long as the piston 16 is moving upwardly within the cylinder 10, the pressure in the chamber 110 is bled off at a sufliciently high rate to maintain the magnitude of the pressure in the chamber 110 below the value necessary to move the valve member 100 upwardly. However, as soon as the piston 16 decelerates in the cylinder 10, such deceleration beginning when the piston 16 closes off the aperture 18 and is cushioned by the air above the aperture 18, the pressure in the chamber 110 builds up rapidly to a magnitude suflicient to move valve member 100 upwardly thereby exhausting the air below the piston substantially simultaneously with the arrival of the piston at the top of its retracting stroke. This timing of the operation of the valve member 100 with the movement of the piston 16, ensures that the free piston 16 is fully retracted before the pressure below the piston is exhausted, and further ensures that the pressure below the piston 16 is connected to exhaust to initiate downward movement of the piston concomitant with the arrival of the piston at the top of its return stroke. As soon as the valve member 100 reaches the retracted position, another cycle of the piston and its control system is accomplished, and this cycling continues as long as pressurized fluid is supplied to the control system.

It should be noted that the interval of time between the moment when the valve member 100 reaches its lower position and when it is returned to its upper position, such interval being determined by the time required for retracting the piston, is a function of the inertia of the valve member 100 and the piston 16 and the fixed differential between the pressures of the fluids 1' and r (as this differential pressure brings about the retraction of the piston 16); and accordingly, this interval is independent of variations in the pressure of the fluids r and r In order to control the frequency of impacts of the piston 16, the throttle valve 93 is manually adjusted for controlling the rate of increase of the pressure of the fluid t, and therefore, the time interval between the moment at which the valve member 60 reaches its up or sensing position, such being substantially simultaneous with the engagement of the piston 16 with the anvil 14, and the moment at which the valve member 100 reaches its lower position for initiating a retraction of the piston. This time interval is substantially independent of the pressure of the r fluid, and varies only slightly with a change in this pressure because the rate of increase of the pressure of the fluid t varies only slightly with an increase of the pressure of the fluid r for any given position of the valve 93.

In order that the upward bias on the valve 109, which the fluid t is adapted to overcome, remains substantially constant notwithstanding a change in the pressure of the fluids r and r the effective area upon which the fluid r acts when the valve 100 is in the up or piston extending position-Le, the area of the diaphragm 102 minus the projected area of the seal 122 and the enlarged portion 123 of the valve member 100 adjacent thereto-is made to be substantially equal to the effective area upon which the fluid r acts; and, therefore, as the pressure of the fluid r increases, the summation of forces created on the valve member 100 by the fluids r and r remains constant. Consequently, the time interval between the moment when the valve 60 reaches its up position and the moment when the valve member 100 is actuated downwardly is substantially constant, and a change in the vibrator impact does not substantially change the impact frequency.

The remaining time interval in the cycle of the piston and its control system which has not yet been considered is that period between the moment when the piston arrives at the top of its stroke and the moment when the valve member 60 reaches its up or sensing position. This interval is aflected by the time for extending the piston to the impact position and is, therefore, affected by the pressure of the fluid r though only slightly.

The control system of this invention, therefore, provides independent controls for the piston impact magnitude and the frequency of impacts whereby each control is substantially ilnaflected by an adjustment or variation in the other. Further, the control system ensures that the piston is fully retracted before it is again actuated and yet terminates the retracting fluid pressure created force substantially simultaneous with the full retraction of the piston, thereby ensuring a maximum piston stroke and eliminating piston hesitation at the top of its stroke.

As will be apparent to persons skilled in the art, various modifications and adaptations of the structure above described will become readily apparent without departure from the spirit and scope of the invention, the scope of which is defined in the appended claims.

I claim:

1. A control system for an impact device having an impact piston movable within a cylinder between a retracted position and an impact position, comprising; a first pressurized air source, a second pressurized air .source, the pressure of said second source being greater than the pressure of said first source, a first conduit connecting the first source to one end of the cylinder to urge the piston to the impact position, a second conduit connecting the second source to the other end of the cylinder to urge the piston to the retracted position, and control means including means responsive to the position of the piston Within the cylinder periodically connecting said other end of the cylinder to exhaust.

2. A control system for an impact device having an impact member movable in impacting and retracting directions, comprising; a first pressure regulator adapted for connection to a pressurized fluid source for providing a first regulated pressure fluid, a second pressure regulator adapted for connection to a pressurized fluid source for providing a second regulated pressure fluid, said second regulated pressure fluid having a pressure greater than the pressure of the first regulated pressure fluid, a first conduit connecting the outlet of the first pressure regulator to the impact device for urging the impact member in one direction by the first pressure fluid, a second conduit connecting the outlet of the second pressure regulator to the impact device for urging the impact member in the other direction by the second pressure fluid, control means having positions blocking and unblocking the second conduit for controlling the flow of fluid therethrough, and means responsive to the position of the impact member cycling the control means between its blocking and non-blocking positions.

3. The control system of claim 2 further comprising means on said first pressure reguiator for adjusting the pressure of the first regulated pressure fluid, and means on said second pressure regulator maintaining the pressure of the second regulated pressure fluid a substantially fixed amount greater than the pressure of the first regulated pressure fluid.

4. A control system for an impact device having an impact piston movable within a cylinder between a retracted position and an impact position, comprising; a first pressurized fluid source, a second pressurized fluid source, the pressure of said second fluid source being greater than the pressure of said first fluid source, a first conduit connecting the first fluid source to one end of the cylinder to urge the piston to the impact position, a second conduit connecting the second fluid source to the other end of the cylinder to urge the piston to the retracted position, a first valve having a first position conmeeting the other end of the cylinder to exhaust and a second position, a throttle valve, a second valve having a first position connecting one of the pressurized fluid sources to the throttle valve inlet and a second position connecting the throttle valve outlet to exhaust, means responsive to the position of the impact piston moving the second valve from its second position to its first position, and means including the pressure fluid in the throttle valve ontlet moving the first valve from its first position to its second position.

5. A control system for an impact device having an impact member movable between a retracted position and an impact position, comprising; a first pressurized air source, a second pressurized air source, the pressure of said second air source being greater than the pressure of said first air source, a conduit connecting the first pressurized air source to the impact device for urging the impact member to its impact position, a first valve having a first and a second position, means responsive to the position of the impact member within the impact device moving the first valve to its first position, a throttle valve, a second valve having a first position connecting the second pressurized air source to the impact device for urging the impact member to its retnacted position and a second position connecting the impact device to exhaust, said first valve in its said first position connecting one of the pressurized air sources to the throttle inlet and in its said second position connecting the throttle outlet to exhaust, means biasing the second valve to its second position, means including the pressure fluid in the throttle outlet moving the second valve to its first position, and means moving the first valve to its second position upon movement of the second valve to its first position.

6. A control system for an impact device having an impact member movable between a retracted position and an impact position, comprising: a first pressure regulator adapted for connection to a pressurized fluid source for providing a first regulated pressure fluid, a second pressure regulator adapted for connection to a pressurized fluid source for providing a second regulated-pressure fluid, a first conduit connecting the first pressure regulator to the impact device for urging the impact member to one of the impact and retracted positions by the first pressure fluid, a first two-position valve, means biasing the first valve to a first of said two positions, means responsive to the position of the impact member within the impact device moving the first valve to a second of said two positions, a second two-position valve, said second valve having a first position connecting the second pressure regulator to the impact device for urging the impact member to the other of said positions by the second pressure fluid, said second valve having a second position connecting the impact device to exhaust, said first valve in its second position connecting one of the regulated pressure fluids to the second valve for providing a control fluid therefor, means biasing the second valve to its second position, and means including said control fluid moving the second valve to its first position.

7. A control system for an impact device having an impact piston movable Within a cylinder between a retracted position and an impact position, comprising: means including a first pressurized fluid for urging the impact piston to one of said retracted and impact positions, a two-position valve, a second pressurized fluid, said valve having a first position adapted for connecting the second pressurized fluid to one end of the cylinder for urging the impact piston to the other of said retracted and impact positions, one of said pressurized fluids having a greater pressure than the other pressurized fluid, said valve having a second position connecting said one end of the cylinder to exhaust, and valve operating means including means responsive to the position of the piston within the cylinder moving the valve between its first and second positions.

8. A control system for an impact device having an impact member movable between a retracted position and an impact position, comprising: a first pressure regulator adapted for connection to a pressurized fluid source for providing a first regulated pressure fluid, a second pressure regulator adapted for connection to a pressurized fluid source for providing a second regulated pressure fluid, a first valve having first and second positions, means biasing the first valve to said first position, means responsive to the position of the impact member within the impact device moving the first valve to said second position, a throttle valve, a second valve having first and second positions, said second valve in said first position connecting the second regulated pressure fluid to the impact device for urging the impact member to one of the retracted and impact positions, a conduit connecting the first regulated pressure fluid to the impact device for urging the impact member to the other of said retracted and impact positions, said first valve in said second position connecting one of the regulated pressure fluids to the throttle inlet and in said first position connecting the throttle outlet to exhaust, means biasing the second valve to its second position, and control means including the pressure fluid in the throttle valve outlet moving the second valve to its first position.

9. A control system for an impact device having an impact piston movable within a cylinder between a re tracted position and an impact position, comprising: a first pressure regulator adapted for connection to a pressurized fluid source for providing a first regulated pressure fluid, a second pressure regulator adapted for connection to a pressurized fluid source for providing a second regulated pressure fluid, a first conduit connecting the first pressure regulator to a first end of the cylinder for urging the piston to the impact position by the first pressure fluid, a second conduit connecting the second pressure regulator to the other end of the cylinder for urging the piston to the retracted position by the second pressure fluid, and control means including means responsive to the position of the piston within the cylinder periodically connecting one of said ends of the cylinder to exhaust.

10. The control system of claim 9 further comprising, means on said first pressure regulator for adjusting the pressure of the first regulated pressure fluid, and means on said second pressure regulator for maintaining the pressure of the second regulated pressure fluid a substantially fixed amount greater than the pressure of the first regulated pressure fluid, and wherein said control means periodically connects said other end of the cylinder to exhaust.

11. A control system for an impact device having an impact piston movable within a cylinder between a retracted position and an impact position, comprising: a first pressure regulator adapted for connection to a pressurized fluid source for providing a first regulated pressure fluid, a second pressure regulator adapted for connection to a pressurized fluid source for providing a second regulated pressure fluid, means on said second pressure regulator for regulating the pressure of the second regulated pressure fluid a fixed amount greater than the pressure of the first regulated pressure fluid, a first conduit connecting the first pressure regulator to one end of the cylinder for urging the piston to the impact position by the first regulated pressure fluid, a second conduit connecting the second pressure regulator to the other end of the cylinder for urging the piston to the retracted position by the second regulated pressure fluid, and control means periodically connecting said other end of the cylinder to exhaust.

12. A control system for an impact device having an impact piston movable within a cylinder between a retracted position and an impact position, comprising: means urging the impact piston to one of said retracted and impact positions, a two-position valve, a throttle valve having an inlet and an outlet, said two-position valve having a first position adapted for connecting a pressurized air source to the throttle valve inlet and a second position connecting the throttle valve outlet to exhaust, means urging the two-position valve to one of said positions, pressure operated means including means responsive to the position of the piston in the impact device moving the two-position valve to the other of said positions, and means responsive to the throttle outlet pressure moving the impact piston to its retracted position.

13. A control system for an impact device having an impact piston movable within a cylinder between a retracted position and an impact position, comprising; means urging the piston to one of said retracted and impact positions, a two-position valve having a first position adapted to connect a pressurized air source to one end of the cylinder for urging the piston to the other of said retracted and impact positions, said two-position valve having a second position connecting said one end of the cylinder to exhaust, means for urging the twoposition valve to one of said positions, a throttle valve having an inlet and an outlet, means for supplying a pressurized fluid to the throttle valve inlet, and means including the pressurized fluid in the throttle outlet moving the two-position valve to the other of said two positions.

14. A control system for an impact device having an impact piston movable within a cylinder between a retracted position and an impact position, comprising; means for urging the impact piston to one of said retracted and impact positions, a two-position valve having a first position adapted for connecting a pressurized air source to one end of the cylinder for moving the impact piston to the other of said retracted and impact positions, said two-position valve having a second position connecting said one end of the cylinder to exhaust, means urging said two-position valve to one of its said positions, a throttle valve having an inlet adapted for connection to a pressurized air source and an outlet, means including the pressure fluid in the throttle valve outlet moving the two-position valve to the other of its said positions, and means responsive to movement of the two-position valve to its said other position reducing the pressure of the fluid in the throttle valve outlet.

15. A control system for an impact device having an impact piston movable within a cylinder between a retracted position and an impact position, comprising; means urging the pistonto one of said retracted and impact positions, a first two-position valve having a first position adapted to connecta pressurized air source to one end of the cylinder for urging the piston to the other of said retracted and impact positions, said first twoposition valveflhaving a second position connecting said one end of the cylinder to exhaust, means for urging the first two-position valve. to one of said positions, a throttle valve having an inlet and an outlet, a second two-position valve having a first position adapted for connecting a pressurized air source to the throttle valve inlet and a second position, means including the pressure fluid in the throttle valve outlet moving the first two-position valve to the other of its said positions, and means cycling said second two-position valve.

16. A control system for an impact device having an impact piston movable within a cylinder between a retracted position and an impact position, comprising; means for urging the impact piston to one of said retracted and impact positions, a first two-position valve having a first position adapted for connecting a pressurized air source to one end of the cylinder for urging the impact piston to the other of said retracted and impact positions and a second position, means urging said first two-position valve to one of its said positions, a second two-position valve having a first position adapted for connecting a pressurized air source to said first two-position valve, and a second position, means including the pressurized air from the second two-position valve moving the first two-position valve to the other of its said positions, and means cycling said second two-position valve.

17. A control system for an impact device having an impact piston movable within a cylinder between a retracted position and an impact position, comprising; means including a first pressurized fluid urging the impact piston to one of its said retracted and impact positions, a two-position valve, means urging the valve to a first of said positions, means responsive to the position of the piston within the cylinder moving the valve to a second of said positions, and means including a second pressurized fluid controlled by said valve moving the piston to the other of said retracted and impact positions, one of said pressurized fluids having a greater pressure than the other pressurized fluid.

18. A control system for an impact device having an impact piston slideably mounted within a cylinder between a first end thereof and a second impact end thereof, comprising; a first passage in said cylinder spaced from the first end thereof providing a piston cushion chamber thereabove, a second passage in said cylinder positioned between said first passage and the impact end of the cylinder, said second passage communicating with an end of the cylinder when the piston is at the opposite end thereof, conduits adapted for connecting a supply of pressurized fluid to opposite ends of the cylinder, control means operated by the pressure fluid in the said second passage controlling the admission of fluid to an end of the cylinder, and manually adjustable regulator means regulating the pressure of the fluid in at least one end of the cylinder.

19. A control system for an impact device having an impact piston movable within a cylinder between a retracted position and an impact position, comprising; means for urging the impact piston to one of said retracted and impact positions, a valve housing, a valve member movable between first and second positions within the housing, said valvehousing having a valve chamber with an inlet adapted for connection to a pressurized air source, said valve member when in its first position connecting the chamber to one end of the cylinder for moving the impact piston to the other of said retracted and impact positions by the pressurized air, and means cycling the valve member between its first and second positions,'said valve member having a piston area communicating with said chamber and positioned for creating a force from the air pressure in the chamber urging the valve member to its second position whereby the pressure created force on the piston area is initially reduced when the valve member moves to its first position due to the pressure drop within the chamber and subsequently increases as the piston reaches its retracted position.

20. A control systemfor an impact device having an impact piston movable within a cylinder between a retracted position and an impact position, comprising; means for urging the impact piston to one of said retracted and impact positions, a valve housing, a valve member movable between first and second positions within the housing, aid valve housing having a valve chamber with an inlet adapted for connection to a pressurized air source, said valve member when in its first position connecting the chamber to one end of the cylinder for moving the impact piston to the other of said retracted and impact positions by the pressurized air, means cycling the valve member between its first and second positions, said valve member having a piston area in communication with the valve chamber and positioned for creating a force from the air pressure in the chamber urging the valve member to one of its said positions, and means disconnecting said communication between the chamber and the piston area as the valve member moves to its other of said positions whereby the valve member moves between its positions with a snap action.

21. A control system for an impact device having an impact piston movable within a cylinder between a retracted position and an impact position, comprising; means for urging the impact piston to one of its said retracted and impact positions, a valve housing, a valve member movable between first and second positions within the housing, said valve housing having a valve chamber with an inlet adapted for connection to a pressurized air source, said valve member when in its first position connecting the chamber to one end of the cylinder for moving the impact piston to the other of said retracted and impact positions by the pressurized air, means cycling the valve member between its first and second positions, said valve member having a first piston area in communication with the chamber and positioned for creating a force from the air pressure in the chamber urging the valve member to its second position, said valve member having a second piston area in communication with the chamber and ositioned for creating a force from the air pressure in the chamber urging the valve member to its first position, and means disconnecting the communication between the chamber and the second piston area as the valve member moves to its second position.

22. For use in a control system regulating a control fluid, a valve assembly comprising, a valve housing having a first passageway adapted for connection to a fluid pressure source and a second passageway, a valve member mounted for reciprocable movement within the valve housing and having a first position connecting the first and second passageways and a second position disconnecting said passageways, said valve member having a first piston area in communication with said first passageway and positioned for creating a force from the fluid pressure in the first passageway urging the valve member to its second position, said valve member having a second piston area in communication with said first passageway and positioned for creating a force from the fluid pressure in the first passageway urging the valve member to its first position, and means disconnecting the communication 11,, between the second piston area and the first passageway as the valve member moves to its second position whereby the valve member moves between its positions with a snap action.

23. For use in a control system regulating a control fluid, a valve assembly comprising; a valve housing having two annular chambers therein with an inwardly extending annular flange therebetween, said housing having a fluid inlet passage connected to a first of said chambers and an outlet passage connected to a second of said chambers, and a valve member movable within said housing and having a first piston area movable in said second of said chambers, said valve member having a first position connecting said first and second chambers and a second position disconnecting said chambers, said valve member having a second piston area in communication with said inlet passage and positioned for creating a force from the fluid pressure in the inlet passage urging the valve member to its second position.

12 24. The valve assembly defined in claim 23 wherein the said first piston area is positioned for creating a force from the fluid pressure in the second chamber urging the valve member to its first position and wherein said first piston area is less than said second piston area.

References Cited in the file of this patent UNITED STATES PATENTS 1,103,104 Tismer July 14, 1914 1,717,818 Thomas June 18, 1929 2,376,519 Stacy May 22, 1945 2,684,661 Keiter July 27, 1954 2,770,222 Anderson Nov. 13, 1956 2,933,068 Johnson et al Apr. 19, 1960 3,004,523 Christensen Oct. 17, 1961 FOREIGN PATENTS 498,963 Belgium Feb. 15, 1951 913,324 France Sept. 4, 1946 

1. A CONTROL SYSTEM FOR AN IMPACT DEVICE HAVING AN IMPACT PISTON MOVABLE WITHIN A CYLINDER BETWEEN A RETRACTED POSITION AND AN IMPACT POSITION, COMPRISING; A FIRST PRESSURIZED AIR SOURCE, A SECOND PRESSURIZED AIR SOURCE, THE PRESSURE OF SAID SECOND SOURCE BEING GREATER THAN THE PRESSURE OF SAID FIRST SOURCE, A FIRST CONDUIT CONNECTING THE FIRST SOURCE, TO ONE END OF THE CYLINDER TO URGE THE PISTON TO THE IMPACT POSITION, A SECOND CONDUIT CONNECTING THE SECOND SOURCE TO THE OTHER END OF THE CYLINDER TO URGE THE PISTON TO THE RETRACTED POSITION, AND CONTROL MEANS INCLUDING MEANS RESPONSIVE TO THE POSITION OF THE PISTON WITHIN THE CYLINDER PERIODICALLY CONNECTING SAID OTHER END OF THE CYLINDER TO EXHAUST. 